Question 22745: Negative Indices Are Outside This Catalan Domain

Original question and givens

Use negative integer n=-20. Give (n, in_domain, value_or_null, boundary).

• G001 — Use negative integer n=-20. Give (n, in_domain, value_or_null, boundary).

Definition and scope

Use the original question domain, assumptions and cited MKO definitions. This item has second-context mathematical and bilingual review, with the model, answer and every arithmetic step independently recomputed from the original parameters; the source question remains a candidate.

• mko-catalan-numbers

Step-by-step derivation

source operation=catalan-negative-index-boundary;original snapshot and mathematics retained

explicit ordered source output fields=[n, in_domain, value_or_null, boundary]

ORIGINAL negative n=-20

in_domain=No;value_or_null=null;this declared sequence startsC0=1,not a negative-index extension

Reverse checks

• S002 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
• S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

(-20, No, null, Catalan_domain_is_natural_numbers_including_zero)

The full substitutions and premise checks give the original answer; source identity,format and status are unchanged.

This question review and source binding

Review date: 2026-10-26

Original questions, answers, step expressions, numeric ASTs and historical records are retained. Source candidate labels remain historical and are not overwritten as formal proof.